Most of this book is theoretical. In parallel with describing T1 engineering, it discusses how engineering features apply to T1 systems as they are built and deployed in the real world. All the theory comes together in the final chapter on troubleshooting, which applies the theory to solving problems. Here is a breakdown of the chapters.
Chapter 1, traces the history of the telephone network in the U.S. from Alexander Graham Bell’s first patent to the modern digital network that carries a great deal of Internet data.
Chapter 2, provides a short overview of all the components that must work together to get a T1 running.
Chapter 3, describes the basic building block of the T-carrier system in the U.S., the single voice channel.
Chapter 4, explains how the building blocks are put together to form a T1.
Chapter 5, presents the need for tightly controlled timing relationships between T1 components and explains several common timing architectures.
Chapter 6, clarifies the role of the CSU/DSU, one of the most important, yet least understood, pieces of equipment in the T1 system.
Chapter 7, walks you through the process for turning up a T1.
Chapter 8, describes one of the oldest link layer framing protocols ever standardized, the High-level Data Link Control protocol. With this chapter, the book shifts from the hardware realm of the physical layer to the software realm of packets, addressing, and framing.
Chapter 9, describes the Point-to-Point Protocol standard. PPP was designed with great flexibility and can run on links from the lowliest analog dial-up line to the SONET links at the Internet core. The purpose of this chapter is to introduce PPP and how it relates to data communications on T1 links.
Chapter 10, introduces another link layer protocol derived from HDLC. Frame relay is a set of specifications that allow transmission capacity to be shared by multiple subscribers, and it is often the most cost-effective way to connect to larger networks.
Chapter 11, has several charts and tables that lay out my accumulated T1 debugging wisdom and experience, plus the vicarious experience I have gathered by speaking with even older wizards.
Appendix A, delves into the details of T1 as the telephone company sees it. High-speed modems rely on having only one conversion between digital and analog transmission, so they depend on service providers to deploy digital telephone technology. In the U.S., service providers can choose between channelized T1 and primary rate ISDN. Both can deliver up to 24 telephone calls digitally to an ISP.
Appendix B, builds on Chapter 9 by describing how to use multilink PPP to aggregate several small links into a larger logical link. Multilink PPP can be used with multiple T1s for increased speed, but it is more frequently used by subscribers to logically tie multiple modem or ISDN connections together.
Appendix C, explains the architecture used to collect T1 link performance statistics. In addition to “soft” factors such as response time and guaranteed repair time, telco service level agreements may include “hard” factors such as upper bounds on bit error rates.
Appendix D, describes the T1-related MIBs. T1 administrators can use the DS1 MIB for T1-related statistics. Depending on the link layer in use, it may also make sense to monitor statistics from the frame relay DTE MIB and the PPP MIBs.
Appendix E, has pinouts for the serial connectors and jacks that are commonly used in T1 systems.
Appendix F, is an annotated bibliography of standards documents relating to T1.
Finally, the Glossary lists terms and acronyms that are often used in T1 networking and defines common terms used by telephone companies. (When in Rome, it helps to speak Latin.)
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